Cotton (Gossypium hirsutum.) is a vital commodity, and fiber and cash crop grown as an important part of cropping systems around the globe. However, Pakistan's production has not been according to its potential for many years. Its production and yield have decreased in Pakistan due to the loss of genetic diversity and lack of empirical research. Therefore, the current research was performed to evaluate the genetic diversity for sixteen yield components among 19 local and one exotic cotton (Gossypium hirsutum L.) genotypes. The experiment was conducted at the experimental site of the Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad. The experiment was performed under the Randomized complete block design (RCBD) with two replications. Analysis of variance revealed significant differences among all traits for available genotypes. The mean value for seed cotton yield ranged from 106.8 to 35.5 g. Genotype ZB-18026 displayed the maximum mean value, whereas genotype ZB-18032 showed the minimum mean value for this particular trait. High heritability coupled with high genetic advance was calculated for most traits. Lint mass per seed showed the highest heritability value (99.99%). Lint mass per boll showed the lowest value of heritability coupled with genetic advance. The phenotypic coefficient of variance (PCV) was higher than most traits' corresponding genotypic coefficient of variance (GCV). Boll weight manifested the highest PCV (68.7088%) and GCV (61.0473%). While traits, such as seed index and fiber strength, showed low values of GCV and PCV. The information related to the genetic variability of genotypes for various traits can be utilized as a basis for further genetic evaluations for future breeding programs.

Cotton is very important crop regarding the global trade. It is grown for its fiber and edible oil in Pakistan. It contributes 1.5 percent to GDP and 69 percent in foreign exchange. There is need to enhance the yield per unit area of cotton by developing high yielding and stress tolerant varieties. In breeding program the parents and their crosses are selected on the basis of their combining ability. Combining ability analysis is performed to identify the general and specific combiner for yield attributed traits. This research was performed for evaluation of four lines as female parents (C-1, CIM-616, TIPO-1 and CYTO-608) and three testers as male parents (NIAB-1048, CYTO-124 and CIM-600) of cotton (Gossypium hirsutum L.). The traits such as plant height, first fruiting node, seed cotton yield, monopodial branches, sympodial branches, ginning out turn percentage, number of bolls per plant, height to node ratio and cotton seed yield was tested. The general combining ability of parental lines and specific combining ability of the F1 cross will be determined for yield related traits. The genotypes with good general combining ability and specific combining ability further exploited for hybrid/variety development programs. For most of the traits like number of monopods per plant, boll weight per plant, seed cotton yield, number of nodes per plant, 1st fruiting node, intermodal distance, ginning out turn percentage, cotton seed yield, seed index, plant height, fiber strength, fiber length, fiber uniformity and fiber fineness value had more value for dominance variance. The higher effects of GCA and SCA indicated that there is the role of additive and non-additive gene action for inheritance of traits.